Numerous machines are available for wrapping or packaging articles or products, which machines utilize various materials such as plastic films, shrink films, paper, coated paper, metal foils and other thin sheetlike substances. These machines, which effect wrapping, bagging or pouch-making, normally operate in an intermittent manner, and numerous varieties of such machines are well known.
To permit more efficient utilization, some of these machines have imprinters mounted on or associated therewith. These imprinters utilize a pigmented ribbon in association with a heated printing head for permitting the desired data to be imprinted on the package or web associated with the packaging machine. In this manner, either constant or variable data, such as information relative to identity, ingredients, quality and manufacturing information, code dating and the like, can be easily and efficiently printed on the packaging material. While several such imprinters are commercially available for use with packaging machines, nevertheless most of the known imprinters have been mechanically and operationally complex. For example, most of the known imprinters have employed a pair of drive mechanisms, one for moving the heated printed head and the other for advancing the pigmented ribbon, thereby complicating the overall assembly and requiring more complex controls. Also, many of the known imprinters have experienced difficulty in controlling the unwinding and feeding of the ribbon during the machine's intermittent operation due to the continually decreasing size of the ribbon spool, and the resulting change in the inertia and movement thereof.
Accordingly, it is an object of the present invention to provide an improved imprinter designed specifically for use on or in association with an intermittent-motion packaging or wrapping machine, which imprinter represents a significant improvement over known imprinters, specifically by improving the imprinter with respect to the known disadvantages mentioned above.
The improved imprinter of the present invention is provided with a single driving device for controlling both the movement of the heated printing head and the intermittent advancing movement of the pigmented ribbon. The single driving device preferably comprises a reciprocal fluid-pressure cylinder for causing the advancing and retracting movement of the printing head. A motion-transfer mechanism drivingly joins the printing head to the take-up reel for the pigmented ribbon. This mechanism is of the one-way type so as to effect rotation of the take-up reel, and advance of the pigmented ribbon, only when the printing head is being retracted. This mechanism also employs a lost-motion connection therein so that the movement of the ribbon is delayed relative to the initial retraction of the printing head, whereby the printing head is initially moved out of engagement with the ribbon prior to the advancing thereof.
The improved imprinter of the present invention also employs a variable braking mechanism associated with the ribbon supply reel, which braking mechanism senses the size of the ribbon spool and imposes a braking force thereon which is approximately proportional to the size of the spool, whereby the braking force is reduced as the spool size is reduced. This controls the rotational movement of the supply spool and prevents inertial overrunning thereof, and also maintains a substantially constant tension in the ribbon withdrawn from the spool.
Other objects and purposes of the present invention will be apparent to persons familiar with apparatus of this type upon reading the following specification and inspecting the accompanying drawings.